Unity - Spending a Month with My Sister [v.2025.11] [Yakumo milk]

Review based on version 2025.11, 100%'d the game with no cheats

Rated a 5/5 for enjoyment, for a critique rating I would do 4/5 or 4.5/5 but at the time of writing this review the game is still incomplete overall which I feel like is unfair to base ratings off of (even though most of the main part of the game is complete)

Gameplay:
It's a pretty simple trainer type game, so if you don't like those types you probably won't like the gameplay of this (but then you can just use cheats or a 100% save). The training itself doesn't feel too grindy (unless you take in the cat and don't know what the optimal actions to take are) and was enjoyable in my opinion. The progression felt satisfying and made the h-scenes even more enjoyable which should be the goal of games like this. The gallery also tells you how to unlock specific scenes/endings without having to wonder how to get them and also features an endless mode if you want to aim for specific scenes.

For negatives I do wish there were more different dialogues. It's not that there's too little but it would definitely be even more enjoyable if the current amount of dialogues were expanded on. But the game is still in development so maybe the dev will add a lot more eventually.

Story:
Simple and believable background story along with realistic events that happen throughout the game. Slowly getting to know and interacting with the sister is nice and fluffy (until you run out of new dialogue, then you're just chasing new scenes). The various endings are also nice in my opinion, the other heroine (shop clerk) is also cute but unfortunately only has barebone content currently.

Art + H-Scenes:
I very much like the dev's art style, both heroines are very cute and all of the art throughout the game feels fitting and enjoyable to see. The one negative that comes to mind is the shower sex scene which for some reason has strange looking art for the dick and pussy that doesn't match the rest of the scenes. Maybe the version I used replaced it with a strange texture but I was too lazy to remove the mods and check.

I found all of the h-scenes hot and there's even minor differences such as how for the blowjob scene when hypnotizing her she deepthroats you on your own vs normally you facefuck her at the same speed setting. The only negative for me would be that there's no regular scene for cowgirl, it only appears as an ending CGI. But surely the dev will add one eventually to cover all scene types.

Sound:
Apparently the old version of the game had voice acting, but the new one doesn't unfortunately. I wonder why he didn't reuse the old VA he had? I didn't play the old one so I wouldn't be able to say. Other than that the music is very pleasant and fitting, same for the h-scenes sfx. Nothing stuck out to me as bad/negative throughout the game for both music and sfx.

Translation:
This version the dev added his own MTL English translation. It's pretty solid overall, but not all parts of the game are translated so you'll still want to use bepinex's auto translator. The auto translator doesn't work on the sound bubbles and those aren't translated yet either so that's unfortunate.

Overall:
I very much enjoyed this game, enough to consider even supporting the dev in the future. Will definitely watch to see how the game develops and revisit it over time. From what I've seen the dev is very consistent and passionate about working on the game, and is also very communicative both with the community and about his future plans.

Good graphics, but if you plan to play... prepare yourself for some "daddy issues," even if you're playing as "Big Brother."

Keep in mind that at some point in the story, the little sister will return home to spend a day with Daddy, even if she's supposed to be at home with her brother. However, the MC's mom calls the MC saying that Daddy is sad, missing the baby girl too much, and is even thinking about quitting his job if the baby girl doesn't come home...
So, in my mind, I imagined something going on between Daddy, Mommy, and the baby girl... but of course, Daddy taught his daughter that all men are like a "bad wolf," including the brother.

You can even cum inside your little sister, and there will be no consequences... she won't get pregnant, and she'll still return home to her daddy.

Leaving that aside, there's the fact that the gameplay loop is... let's say limited and could have had more content... "Oh, but there's a time limit"...
I'm not really into time limits in games... since I'm playing a game for fun... but I could add more content with a longer time limit... or at least remove the daddy from the story and put Mommy in the game with the MC along with his little sister.

Summary:
Good graphics... "Meeh" gameplay, could have some voice acting, it would make a huge difference... and the game itself discourages the player from playing the endless mode... why put it in then?

So I played it, finished it quickly, and then I'll forget about the game, just the way the gameplay mechanics were designed to be.

Unga Bunga

Translation:
"I was really surprised that I'd like this one, I usually don't go for the younger sister in school type of thing but I was won over by the way the game itself.

- Gameplay
It's a dating sim. You have 30 in game days in the story mode but so far it keeps things at a fair enough pace that you don't need to worry about losing time. Endless mode is essentially no time limit but you get no ending/ story ending or whatever. General idea is to get your sister's love and lust levels high enough to unlock sex positions and so on. Give gifts, teach her about positions, all that fun stuff. It's also a time management game, you have to weigh what is important while also managing your health (stamina) throughout the day. I'm assuming as well that you will have other women you can have sex with too, after a certain area opened up you can chat with the new woman there which feels like she will be opened up as potential side girl or other love interest. It can be a grind if you aren't on top of everything, otherwise I had no trouble keeping things in the green and losing affection from her.

- Storyline
Your sister is staying with you because your father wants her to learn about boys and sex. At least that's what I gathered from it all. As you teach her more and more, she starts to feel closer and more in touch with you. Will you two go further and a step beyond what normal siblings do?

- Artwork
Really well done, honestly the best thing about this game. Everything is both smooth and done well. Only gripes are some scenes look just a little weird, specifically the missionary scene's tits have that 3d look to them which just don't match the aesthetic of everything else.

- Overall
Again I'm usually not a fan of this type of hentai, but I have to give credit to the author in creating something worth a try in my books.

Like I said only gripe really is certain scenes doing a 3d look. Not a big thing as it's not the only scene but just throws the aesthetic off to me."

What can I say? I was glad to find another good game with "sleepers". There are too few of them left, which is quite a shame.

Nice animations, basic plot and not enough bed scenes. The "sisters" thing doesn't really matter to me, but to each his own.

All of this is pleasant, as well as things that some fans of all sorts of peaceful bed games will find "special". In the end, here the maximum education in sex school is given to the younger generation. Of course, we make allowance for the fact that this is still a game for adults... or people with teenage spermotoximosis...

The bad things are the huge interface, the glitchy endless mode, the very short playing time (forcing you to play the same thing more and more) and the lack of content itself. There is only one girl in the game, you have her for a month, and in order to keep her you need to keep the house clean forever (which the cat actively interferes with) and also a bunch of characteristics that give us this or that desired scene with dubious mechanics. The process of obtaining them is painfully weak and the same, alas. And yet the game is good. Very and significant.

If there were voice acting here and more content, it would be priceless. We would somehow survive the grind.

3.5 \ 5
8 \ 10

Finished the 2D version. Pretty good. Kind of awful to have that month limit since it makes unlocking the CG is a pain. I tried for several weekends to unlock the Aho B. but it was literally impossible and having to rewind time meant that I lost the affection/lust or whatever progress necessary to trigger it to begin with. The bath sex scene can be triggered before you can even formally start a relationship with her. All in all that was pretty peak though it's definitely clanky and cumbersome. I played with both cheats turned on so I didn't had to "grind" anything. I have no clue what's the obsession with managing those things in sex games. Let me grind the relationship not the money and stamina counter.

3/5

Not worth downloading/playing unless you really bored and looking for something new.

- graphics/artstyle are around 3,5/5 score, some scenes look better than others, overall its like koikatsu sunshine graphics but worse
- animations are ok, although i didnt find scenes exciting too much, ending one was the best probably
- gameplay is boring and done badly, i tried twice to beat this in normal way then gave up and went cheats route. Stamina cost for anything in this game is way too high and unbalanced, if you keep cat you spend most of day regaining stamina and cleaning house with barely any time left for work, going to shop and fixing stamina issue. Its just endless cycle of stamina management while main purpose is corrupting the girl, i just didnt like it at all. I've played similar games that done it a lot better, although every game of this genre has lots of things that could be improved
- there is barely any change, oh wait, there isnt ANY change in girls behavior when you learn her about hentai stuff and corrupt her, she acts like nothing happened all the time, when you play games like this those small details are the best part of gameplay

I would downarate it to 2/5 for the last part i mentioned but overall its not that bad game, its just screaming for a lot of polish and rework, and i doubt anything will change though. Look for better games than this folks, cus there at least few.

Writing: 6/10
Imagery: 8/10
Gameplay: 7/10
Kinks: 7/10
Overall: 7/10

Spending a Month Fucking My Sister.

What's a horny man to do with a little sister who will be living with him all on her own for the summer? Why pump as many loads into her as possible while she sleeps, and corrupt her into your perfect little cum dump. Unless you just want a normal relationship, in which case, why are you here?

Not gonna lie, I came because I saw sleep sex, and that preview gif looked promising. However that must be from an old build, because it's not in the current version of the game. Yes you can molest her while she snoozes, but there's no penetration any longer, very sad.

The sister is cute, nice design, and really makes you want to do naughty things to her and teach her dirty stuff to fill her growing brain with thoughts of sex, masturbation, and sucking off her big brother.

Overall, very easy game, very sad sleep sex scenes, my search continues.

This review basically covers both versions of the game fundamentally.

It's a pretty simple and tried and true game formula.

You have a limited amount of time to boost up various stats and get closer to the MC's sister so you can bang. It's not an overly complicated game at all, I think if you know what you're doing you could easily figure out in multiple playthroughs some pretty easy methods of increasing your stats and just cheesing it.

It's also a Unity title and doesn't obfuscate the variables either so there's that too.

The sex scenes are a pretty basic loop of animation of the rigged assets and it all looks pretty nice.

The hypnosis minigame though is a crime. There is honestly no way to get the timing of the coin down at all and for some god awful reason I am pretty sure the whole thing is animated at like 15fps or something. The timing is weird. Just speed hack the thing to slow it down honestly.

I've only touched the newer version of the game a bit and just jumped to the gallery just to see what's up. The newer version has a fair number of changes. A resolution bump and some changes to how some scenes are presented.

The sleep play scene has been changed a lot and personally I liked the original version a lot more for all the little things you could do and actual penetration with that one.

But both versions are good in their respective ways and I can recommend them both for a pretty good execution of its setup.

I do wish there was more done with the other girl in this game. I'm not really sure what the purpose of her limited scenes are but I assume it's something you'd get more out of in the dialogue (which in this case is all MTL hit or miss stuff)

I mean, I enjoyed it. I'm not really one for enjoying these kinds of games but the payoff felt mostly worth it.

The graphics are fine, the sister is both cute and hot, their interactions can be both casual and incest-y as you'd probably expect. The grind wasn't that big of a deal for me, I wasn't overly invested through it admittedly but I've played those old flash dating games before and let me say the grind in those compared to this helps you to understand it's not that bad.

While I wouldn't say this is a must-play, I'd still say it's worth trying if this whole brother-sister setting is your thing.

This game has always had a lot of potential, which is why it has always been on my favorites list. With this new March update, the new scenes with her sleeping and the new interactions are excellent! It didn't disappoint me at all, I hope they keep updating and allowing more and more new ''things'' to be done, especially the possibility of getting pregnant and also more items from the store to be able to use. The important thing is to have more and more variety of content <3

Well shit, it's 2025 and I've known about this game for at least 2+ years now. It was nice seeing this game evolve over time and i've kind of developed a weird attachment to this game from all the checking in every few months to see the new updates and reading up on the discussion, not to mention all the furiously jerking off (jesus i've lost gallons to this game).

In the beginning this game was pretty barebones. I could name maybe just like a handful of different h-scenes, but the game has definitely evolved since then and now we've got default h-scenes, nightcrawler, shower stuff, and the random encounter ones which makes this game pretty packed with content.

some people dog on the grind but i think the grind is part of what makes this game work so well. you work like hell grinding up stats and it makes finally getting the scenes feel more rewarding.

but horny stuff aside i just really love the characters and the vibe of this game. super cozy and cutesy characters and a lovely soundtrack that's memorable and really catchy. this game made me both rock hard as diamonds and it melted my heart a little weirdly enough.

this was one of my first h-games and for sure one of the best i've ever played. would highly recommend, plus if you dislike the grinding now you have the option of cheats and gallery. love this game

The game has good art with a good amount of sex scenes for the time played but i'm giving it a 3* because of little problens that become a huge problem together, the uncensor and translation mod made the game playable for us although there are some bug in the translation. The save files are awful, you can only save at night and i didn't find any way to load the save file outside of the title screen but i also didn't find a way to go to the title screen other than to close and open the game again, not sure if the problem is in me and the button is there somewhere.
The story of the game is very simple but it work in giving a context for the scenes so i'm not complaying about it, it has a little grinding but nothing outside of the normal for this type of game you just need to be careful with you money and stamina.
Now this is more of a personal problem with a LITTLE SPOILER:

Its about the most basic sis-con game ever made.

The game has a storyline that can fit the back of a playing card. Basically you're just another random guy that somehow survives on part time jobs (what is it with japs and part time work, its like every fucking H game follows this premise). You have a sister who is cohabiting with you for a month to...erhem ...learn more about males. Yes, needless to say youre gonna fuck her brains out at some point, on her request.

So what with there being a time limit of 31 days, the gameplay mostly centers upon doing various things to increase favourability and sex ed, while balancing your stamina with the need to work (to gain money) and cleaning up the house. Its kinda bizarre because these grind-a-thons dont really give out the best stat bonuses, theyre more like supplements. The best stats are gained via events, or interactions on weekends. In effect youre really grinding because theres nothing much else you can do anyway.

H gameplay is mostly just click and cum, locked behind stat requirements. Bizarrely there is a sleep sex minigame that is vastly more complex than the others, and yet features zero stat requirements beyond buying the book to unlock it.

Aesthetically its about as generic as it gets when it comes to anime, though its certainly appealing. H is animated, though theres no VA.


Conclusion...

I came into this game not expecting much, but was instead pleasantly surprised to find it immensely enjoyable, despite its simplicity. Its the sort of game that does nothing special but got all the basics right. There's no long winded dialogues, unfunny wise cracking, no unrealistic cohabiting context nonsence - put simply, youre asked to play the role of a good brother. Sticking your sausage into her donut is a choice, not an obligation.

The only problem with the game: its too fucking short and is bereft of content. There are shades of the original imouto monochrome here, but while the latter vastly improved upon its initial premise over the last half decade (and so throughly deserved its massive acclaim) this game is content to move at the pace of a snail running a marathon, condemning it to midtier status, never to realise its potential. And that's a darn shame because if this had the same level of content with the current imouto monochrome fantasy, it might actually surpass it.

Oh well, I have no qualms of recommending the game because it made me feel all fuzzy inside and gave me a diamond hard boner. Short as it is, sweetly made.

a good and simple game concept, could be executed better, you have to grind and if you don't pay attention you'll reach the last few days without having done anything and your progress will be reset to some weird newgame+ system.
this is very reminiscent of one of jsk studios earlier sister type games, but this has less interactability, while having more world building (so it evens out?) I enjoyed the writing in what was actually readable but it's very panned out and drags on.

the brother sister interactions are good, they have sibling energy and she's not some stranger that just outright loves you (again this is from what's readable)

All in all a decent game, it's an amazing foundation for more content, but as it is right now it's kind of lackluster and you're grinding for not much reward, if you're bored you'll enjoy it

my meat is numb.
The grind feels rewarding, however, I could do without the random events that can potentially cause MC to faint. The progression could be more gradual as well, however, every scene feels earned and for the most part they all look great. If this is a work in progress, I cant wait to see what the finished product is. I'm 4 hours in and I will definately play more.

There are 4 different scenes (with different backgrounds and whatever).
You grind levels until suddenly she just takes everything like a whore, no transition whatsoever.
Totally not worth the trouble, do not play.

Resource management game done right. You need to really think to succeed, but there are still multiple viable strategies. And for people who consider any resource game a "grind", there's an easily accessible cheat for infinite money and energy. The animations are very good.

My only real issue is lack of build-up / ecchi. Despite living together, they don't develop much sexual tension until eventually they just start having sex. Bathing together is the only example, but there were missed opportunities. Like feeding her a snack could have been more intimate, and we don't get any art for when they start sleeping in the same bed.

I also felt like the set-up was a bit contrived and I didn't really find the character to be interesting, but that's just a preference thing.

Review of [v.2023.07]

This is absolute garbage.

It's grind grind grind and more grind.

You'll also need to manually setup the translation from a post in the thread.

The time it takes to download the game, watching the download bar, was more entertaining than the game itself.
I have no idea HOW it scores so high, considering how little there is to that.. "game".

The soundtrack is abysmal, the gameplay is non existent, the dialogues are as boring as they can be, and the progression, if we can even call it that, is utterly crap.

This is one not worth anyone's time, let alone attention.

Probably is one of the best on going monthly patches game out there, worth giving a shot and sticking around for the development. The game has made a lot of progress although it is slow but surely it all adds up over time

As of the May 2023 update, I can see that the game is about half done and without end game content, unlike other simillar titles. I don't mind waiting, and the game does have features, but something tells me that the development of this game is unusually slow. Other than that, a nice experience and a rarity to enjoy.
Visuals are pleasing if not kind of overdone (I'd take 20% less quality for 2x the content). The artist/dev seems to be perfectionists.
There isn't enough non-ecchi scenes (I know, I'm being dumb here), but I really do think non-ecchi scnes bring out a lot of value. It could literally just be a few still images relative to what's on the sex scenes.
I'm rating this on current but enhanced by what could be added in the future.